The aims of the proposed research are: a) to explore the relations between anger expression and five constructs hypothesized to influence the expression and regulation of anger (awareness of anger, knowledge and use of display rules for anger, knowledge and use of anger control strategies, motivation for anger regulation, and physiological reactivity), b) to investigate the role of sociometric status and aggression in children's anger expression and regulation and in each of the five constructs listed above, c) to explore the relation between four subtypes of aggression and anger expression, and d) to investigate gender differences in children's anger expression and regulation. These aims will allow anger regulation skills to become more integrated into interventions for rejected and aggressive children (Conduct Problems Prevention Research Group, 1992). Classroom data collection will take place in 51 second-grade classrooms. A thirty-minute individual interview with each child will include six parts: a) sociometric nominations, b) peer nominations for overt aggression, c) peer nominations for relational aggression, d) assessment of knowledge and use of display rules for anger, e) assessment of knowledge and use of anger control strategies, and f) assessment of motivation for anger regulation. In addition, teachers will complete ratings of each child's reactive and proactive aggression. A subsample of 300 rejected, average, and popular participants will take part in laboratory data collection. The laboratory protocol will include the collection of the following types of data: a) videotapes of participants interacting with a confederate in two anger-arousing, standardized competitive game paradigms, to be observationally coded for anger expression, b) an interview-based assessment of knowledge and use of display rules for anger, knowledge and use of anger control strategies, and motivation for anger regulation in these two specific paradigms, c) physiological data collected both during the paradigms and while viewing a videotape of the recently completed interactions, and d) self-report of awareness of anger, collected using a video-recall methodology.